Process of oxidizing primary or secondary alcoholic hydroxyl groups or aldehyde groups



Patented July 13, 1948 PROCESS-OF OXIDIZING"PRH\IARY "R,

SECONDARY ALCOHOLIC. HYDBOXYL .GROUIS on mama moors Ladlslaus Guillaume Farkas and O'zias'z 7 Schichter. Jerusalem;l a lestine No Drawing. Application September 28,1945, Se- Q rial No. 619,256; In Palestine October 1, 1944 s Claims. (ci'zso-iesi This invention relates to the oxidation of alcoholic ,hydronl groups or of aldehyde groups. More specifically. the invention is concernedwith the oxidation 01' primary and secondary alkanols and alkanals, and oi similar compounds. .-:The invention has more particularly as its object'to provide a convenient process lor. the. preparation by straight, non-disruptive oxidation of such compounds as are not or only difilcultly. obtainable so far by other methods.

used for the qualification oi the term "oxidation" are'meant to restrict the invention to such oxidation reactions as lead to the removalloi hydrogen from the hydroxyl or aldehyde groups amount of the compound, to be oxidized, and an amount stoichiometrically corresponding to the desiredamount of oxidation product oi. an oxidizing agent, other than bromine, that is capable of oxidizing the bromide ion to elementary bromine under reaction conditions.

. examples of oxidizing agents 01 the class Y "referred to herei'nbeiore, we may employ com pounds containing both halogen and orwgen and/or to the addition thereto of oxygen without the splitting-oi! of carbon atoms irom the mole cule of the compound so treated, with the iorma.-

tion 01-. carboxyl or aldehyde, groups i'rom'prlmary alcoholic hydroxyl group (the carbo wlic'.

acid so formed being usually esterifled with the starting alcohol present in excess) or keto groups The terms stralght" and non-disruptive"..

atoms, suchv as chlorine dioxide and other oxid s, or .chloi-ates bromates, chlorites, bro- ,hypochlorites, perchlorates and perbronia'tes'bi "the-alkalie's, alkaline earths or other metals j'orxnon-metalssuch as the above men.-

'.tioned salts' oi sodium, potassium, calcium, mag- ;nesiuln, or ammonium, or oxides oi amphoteric metalsln valence states 0! at least +4,

such asidi'oxides of. (chlorine) manganese or lead, chromic acid or its salts such as potassium chromate or 'blchromate, manganates or perof sodium, potassium calcium, magfrom secondary hydroxyl groupaand oi carboxyl groups from aldehyde groups.

I The straight, non-disruptive oxidation of many substances of the kind in question can-.be carried out with a great variety of oxidizing agents. However, inthe great majority of known processes of this kind, the reaction is either not complete, or too slow for practical performance for preparation purposes, or accompanied by undesired side reactlons, usually of a disruptive character. In particular, it is known that chlorine can be used as an oxidizing agent for the conversion of alcohols into higher oxidized substances, but usually the use of chlorine for this type of reactions entails the drawbacks stated above. In addition, the chlorine has a tendency to enter the molecule of the compound to-be oxidized as a substituent, particularly at elevated temperatures.

It has now been found that the various drawbacks of known various oxidizing agents can be avoided and a virtually complete, smooth and quick straight, non-disruptive oxidation oi the compoundsoi the kind specified can be obtained. to the virtual exclusion of side'reactions, ii the oxidation is carried out by means'oi oxidizing agents other than bromine in the presence of a relatively small amount oi elementary bromine. 50

Accordingly, this invention consists in a process of oxidizing compounds of the kind referred nesijum,--and other metals. Although these are preferred-elementary chlorine, or oxygen, or ozone may also b'e employed.

The bromine may be initially added to the reaction mixture in elementary form or as a broto, wherein the oxidation is performed by the combined action of an. amount of bromine or calciumbromide or hypobromite.

mide or hypobromite such as sodium, potassium If it is added as a bromide, this will at once be oxidized .to elementary bromine by the oxidizing agent present, and the elementary bromine originally added or thus produced, or the hypobromite, as the case may be, becomes active towards the compound to be oxidized, oxidizes 9. corresponding amount thereof and is thereby reduced itself to bromide, and the cycle begins afresh.

Where a bromate is used as an oxidizing agent and is gradually converted into the bromide, the latter-is produced in a theoretical yield. Since bromate can easily be prepared in a highly pure state, the bromide is correspondingly pure. 'This is especially remarkable in view of the difliculties encountered in the hitherto usual process of reducing bromate to bromide. Accordingly, under another aspect, 'a'particular embodiment of the present invention can be defined as a process oi preparing bromides oi the highest degree 01 purity, wherein a pure bromate is subjected to reduction by the combined action of bromide ion and an organic substance, or a mixture of organic substances, containing one or more primary and/or secondary alcoholic hydroxyl groups and/or aldehyde groups. The bromate stoichiometrically small in proportion to the employed inthis case can-be sodium, ammonium,

. 3 potassium, calcium, magnesium bromate or the bromate of some other metal.

The process according to this invention may be carried out in the presence of a solvent capable of dissolving with the oxidized reaction product. It is even possible, and sometime advantageous, to use as such solvent another portion of the reaction product, whereby a more concentrated solution of the latter is obtained which is easier to be separated and worked up.

Materials that can be used as solvents may be hydrocarbons, halogenated hydrocarbons, acids, esters, ethers, phenols and the like such as benzene, chlorobenzene, acetic acid, propionic acid, ethylacetate, butylether, phenol, cresol or xylenol. The reaction can be carried out at atmospheric pressure, reduced pressure, for example at to 300mm. mercury pressure, or at superatmospheric pressure for example at one to ten atmospheres. The proper pressure range can be conveniently adjusted to the required reaction temperature when the reaction can be carried out at the boiling point of the mixture under refluxing conditions so that the reaction temperature can be kept readily constant.

" dation. reaction can be promoted by catalysts such as copper compounds, e. g., copper bromate; molybdenum compounds, e..g., molybdena or sodium molybdate; and other compounds of catalytic metals such as those of the transitional" elements, which have their differentiating electron in the second from the outermost shell. A convenient-periodic table showing this relationship is shown in the Journal of Chemical Education, August 1939, page 394. The elements of the first-transitional series are those having atomic numbers of 21 to 30 inclusive, those of the second transitional series are those having atomic numbers 39 to 48 inclusive: those of the third transitional series are those having atomic numbers 57 and '72 to 80, inclusive: and those of the fourth transitional group which are now known, the group being as yet incomplete, are those having atomic numbers 89 to 92 inclusive. Examples of suitable metals of this type are titanium, vanadium, chromium, iron, cobalt nickel, columbium, the group of the platinum metals, tantalum and tungsten.

The amount of the oxidation agent employed for each mole of alcohol or other hydroxy compound to be oxidized may be the amount corresponding to 0.2 to 2 gram atoms of available oxygen and preferentially the amount corresponding to 0.3 to 1 gram atom available oxygen. For the, purpose of calculating the amount of the oxidizing agent one mole of calcium bromate corresponds to six gram atoms of available oxygen, one mole sodium hypochlorite corresponds to one gram atom of available oxygen and one mole of chlorine corresponds to one gram atom of available oxy'gen, I

Whenever less than stoichiometric quantities of oxidizing agent is employed the excess of the material tobe oxidized serves as solvent.

The amount of bromine used in conjunction with the oxidizing agent according to the present invention may be 0.01 mole to 0.05 mole for each gram atom of available oxygen-in the oxidizing agent. It is preferred to use free bromine in amounts of 0.02 to 0.2 mole for each gram atom of available oxygen in the oxidation agent.

proved most suitable for the preparation, for example, of estersv of various alcohols with the corresponding acids, such as ethyl acetate or butyl butyrate, or higher Ones like hexyl caproate, lau-' ryl laurate and others for the corresponding alcohols. From various secondary alcohols, the corresponding ketones have been prepared. Where the starting material contains both primary and secondary alcoholic hydroxyl groups, the oxidation of the secondary hydronl group is in general far quicker than that of the primary one. Similarly, where a compound contains a hydroxyl group besides an aldehyde group, the oxidation of the latter is in general much quicker than that of the former. This diflerent behaviour of different grou towards the oxidizing agents can be utilized for conducting the reaction in .a desired direction in preference to taeny undesired oxidation within the same sys- The invention is illustrated in the following examples to which it'is,'of course, not restricted. Where in the following, reference is made to aqueous solutions of calcium bromate and of hydrogen bromide, these .are respectively of 35.5% strength by weight (1.2 molesper kg. of solution) and 44% byweight.

4 Example 1 288 grs.-of ethyl alcoholof 96% strength (corresponding to 6 moles) are mixed in an Erlenmeyer flask with 111 grs. of solid potassium bromate (0.67 mole) and 32 grs. of elementary bromine (02 mole). The mixture is stirred. The reaction which soon sets in is exothermic and causes the mixture to heat. When a temperature of 50 C. is reached the flask is cooled and the mixture is kept at 50 C. for about 6 hours, first by further cooling, later on by slight heating. By this time all the bromate has disappeared and about 82% of the originally added free bromine is reduced to hydrogen bromide. The reaction could be continued until the last traces of bromine have disappeared. However, the reaction becomes' then very slow so that it is preferable to interrupt it and to dispose of the bromine by other means, for example, by way of reduction with sulfide or with an aqueous solution of sulfur dioxide.

From the reaction mixture, in which the ethyl acetate is partly split into acetic acid and ethyl alcohol according to the equilibrium of the system, the ethyl-acetate is recovered by distillation, the distillate being a ternary azeotropic mixture of ethyl acetate, ethyl alcohol and water from which the ester can be separated in known manner.

92 grs. of ethyl acetate are finally obtained, which is ayield of 95% of the theoretical amount calculated by the consumption of bromine and bromate.

The potassium bromide, which is formed in the theoretical amount corresponding to the amount of bromate employed, can. be crystallized from the residue of the distillation. aforesaid and is at once obtained with a high degree of purity which can still be enhanced by re-crystallization.

'The free bromine originally used for the reaction has been converted into free hydrobromic acid mole) are obtained. ,The bulk of the ethyl ace- 1 tate distils spontaneously during the reaction the which is equally contained in said residue and can be recovered therefrom by distillation'as a concentrated aqueous solution at constant boilin point.

r In this example, the alcohol i originally pres-' ent in the reaction mixture in an excess of six times the amount. thereof which is oxidized to acetic acid, or three times the amount contained in the ethyl acetate finally obtained. The concentration of free bromine at any moment of the reaction is about 0.5 mole per liter.

, Comparative tests-have shown that in those cases where the alcohol used as starting material is soluble in water, the excess 01 alcohol has an influence on the speed of the reaction, the

speed being the greater, the greater the excess.

Moreover, the speed of the reaction is substantiallv proportional to the concentration of free bromine in the mixture. v

Example 2 288 grs. of ethyl alcohol of 95% strength (by weight), corresponding to 6 moles,are graduallyrest can be recovered from the reaction mixture by heating the latter after .the reaction has been completed.

Under the thermal conditionsrhere described,

1 the amount of bromine entering the alcohol by way of substitution is not quite negligible. About 5% of the total bromine forms bromo-commixed with 834 grs. of an aqueous calcium bromate solution (1 mole) and 86 grs. of hydrogen bromide solution. In an Erlenmeyer flask provided with stirring paddle and reflux condenser,

the whole amount of alcohol is mixed with the whole amount of hydrogen bromide and 100 grs.

of the calcium bromate solution, the mixture is stirred and within'a-short time spontaneously heats up to boiling. The rest of the calcium bromate solution is then slowly added (through the condenser or a. side-tube provided for thispurpounds, corresponding to a loss of about 1% 01' the oxidizing capacity of the bromate Example 4 1 222 grs. of n-butyl alcohol (3moles) are mixed with-417 grs. of calcium'bromate solution (0.5 mole)- and 54 grs. ot'hydrogen bromide solution. The mixture, which is stratifled in an alcohello and an aqueous layer,-is vigorously stirred and its temperature rises soon to 60 C. The mixture is kept at this temperature, by cooling during about the flrst'30 minutes. and by heating thereafter. About 2 hours after the beginning of the reaction; the brown bromine colour of the 1 mixture has considerably brightened and the reaction'gcan be brought to an 'endqby heating the mixture to oo c, {for about minutes.

Butyl butyratei s.."thus' obtained in a virtually theoretical yield, Thecalcium bromide produced by the-reductionbt-calcium bromate is quantitatively be found inflthe aqueous layer of the reactionmixture, the hydrogen bromide is, about. equally di stributed between the aqueous .a'nd'alcohol'ic layers; .The latteriswashed with pose) within about half an hour at such a 'rate' that the mixture continues to boil while being tion mixture by distillatiton. Its yield is .about 90%. of the theoretical amount.

Example 3 By a slight variation of the conditions described in Example2, acetaldehyde can be obtained as a reaction product besides ethyl acetate. The reaction vessel is connected with an ordinary Liebig condenser instead of with a reflux condenser.

144 grs. of ethyl alcohol (96%), 23 grs. of hydrobromic acid solution and grs. of calcium bromate solution are initially introduced into the reaction vessel. After 5 minutes, the mixture has spontaneously heated up to boiling, first at about 78 C. and gradually rising to 82 C. Thecondensate leaving the condenser is collected. In the course of about 2 hours, further amounts of alcohol and calcium bromate solution are alternatingly and gradually added through a sidetube, up to a total amount of 480 grs. (10 moles) of the former and 500 grs. (0.6 mole) of the latter.

. About minutes after the addition ofthe last portion of bromate, the temperature or the mixture drops below boiling point. It is advisable to (1.4 moles) and 30 grs. of acetaldehyde- (0.68

water, dried with sodium sulfate and rectified.

. Ex l 306 grs. of normal p ary hem alcohol'(3 moles) are mixed with 417 grs. of-aqueous calcium bromate solution and 64 grs. othydrogen bromide solution, and the mixture is vigorously stirred whereupon it warms 'up very quickly. The temperature is held at C., first ,by eooling, then by heating. The. reaction is terminated after- 1 about 3 hours when the colour'brightens considerably. 'If the mixture is then heated to about 60 C. for half an hour, the-free bromine disappears completely. i

Hexyl caproate'is' thus obtained in a yield of I 95% of the theoretical amount.

I Example 6 186 grs. of lauryl alcohol (1 'mole) are mixed with 139 grs.;of calcium bromatesolution and 31 disappeared.

Example"? 304 grs. of 2-benzoxy-ethanol (2 moles), commercially known as Benzyl-Cellosolve (trademark), CcHsCI-IzOCHzCHaOH, are mixed with 111 grs. of solid potassium bromate males), 35 grs. of hydrobromic acid solution and 50'grs. of water, stirred for 4' hours at 50 C., and then heated to 60C. fora short while. -,llhecorrespending ester. a e

cimcmocmcmooccmocmcins forms in a yield of 97% or the theroretical amount, part thereof being saponifled. The ester can be separated from the reaction mixture by distillation in vacuo under a pressureofabout 1 mm. (mercury column), the main fraction distillingat about 103-104fC.

-. Example 8 288 grs. of ethyl alcohol or 96% strength by weight (6 moles) are mixed with 528 grs. or ethyl acetate (6 moles), 278 grs. or calcium bromate solution and 267'grs. of hydrobromic acid solution. The mixture initially stratiflesin two layers. In the course of the reaction, water is formed and the two layers mix. The mixture is itrpt at 50 C. for hours when all the bromate and the major part of the freebromine has been reduced. The rest of bromine is disposed of by means of an aqueous solution of S02. Ethyl acetate is obtained in a yield of more than 90% of theoretical amount.

7 Example 9 288 grs. of ethyl alcohol (96%) are mixed with 81.7 grs. of potassium chlorate moles) and 177 grs. of hydrobromic acid. The mixture is heated to and kept at 50C. for 5 hours and thereafter allowed to stand over night at'room temperature. It then contains about 6 grs. of free bromine per liter which is suitably reduced by means of aque- I ous sulfurdioxide. The yield of ethyl acetate is about 93% of the theoretical amount.

The reaction b'etween chlorate and hydrobromic acid is less easy and complete than that between bromate and hydrobromic .acid. It is for this reasonthat the concentration of the acid is chosenhigher than in the case of bromate.

j vEsrarrrzile 10 144 grs. of ethyl alcohol are mixed with 150 grs. of a molar aqueous cupric bromide solution, the mixturels heated to 50 C., and gaseous chlorine is introduced'at 'the rate of 30 grs. during the first hour, grs. during'the second hour, and 6.5. grs. duringt'a further-half hour. The yleldof ethyl acetateis-ofabout80% of the theoretical amount. About 10% fof'the chlorine used can not beaccounted for and appears to enter as substituent into the organic molecules present. When chlorine acts on alcohol in the absence of bromine, mainly chloral is obtained.

Example 11 288 grs. of ethyl alcohol (96%), 174 of powdered manganese dioxide and 33 grs. of solid potassium bromide are mixed in an Erlenmeyer flask and 327 grs. of sulfuric acid (60%) are gradually added during 2 hours. The mixture is kept at 50 C. with stirring for 4 hours from the beginning of the addition of sulfuric acid. By this time the manganese dioxide has disappeared and the bromine is completely reduced.

Ethyl acetate is obtained in a yield of about 90% of the theoretical amount.

If ethyl alcohol is treated only with manganese dioxide and sulfuric acid in the absence of bromine, the reaction is uncontrollable and besides the formation of acetaldehyde, acetic acid and ethyl acetate, a substantial amount of disruption takes place with the formation of carbon dioxide.

Example 12 is to be found quantitatively in'the aqueous layer. I

Example 13 I If butyl butyrate is prepared by the oxidation of butyl alcohol with sodium bichromate and sulfuric acid according to "Organic Syntheses," edited by H. Gilman (John Wiley a Sons. New York, "Collective Volume I," page 138), the reaction mixture being cooled withice and care being taken that its temperature does not rise above 20 C., the yield is of 41 to 47%. If, however, 1 mole of HBr per liter is added to the reaction mixture which, for the rest, has the same composition, the reaction temperature can be raised to 50 C. and within one hour, butyl butyrate is obtained in a yield exceeding 80%.

Example 14 106 grs. of benzaldehyde (1 mole) are mixed with 55.7 grs. of solid potassium bromate, and 10 grs. of hydrobromic acid solution. The mixture is kept with stirring for 8 hours at 70 C.

Benzoic acid is thus obtained in an almost theoretical yield.

Example 15 '49 grs. of acetaldehyde (1 mole) ar dissolved in 222 grs. of normal butyl alcohol. To the solution 55.7 grs. of solid potassium bromate are added and 8 grs. of bromine are gradually introduced within about 20 minutes. The mixture is kept for 5 hours at 35 C., then the temperature is raised for a short while to 50 C.

Butyl acetate, which can be separated by distillation, is thus obtained in a yield of about 86%.

It is noteworthy that the oxidation attacks the carbonyl group in preference to the carbinol group which gives a possibility of preparing mixed esters.

Example 16 Example 17 93 grs. of Z-dodecanol (0.5 molerare mixed with 34.7 grs. of calcium bromate solution moles) and 7 grs. of hydrobromic acid solution, and the mixture is kept for 20 minutes at 35 C. The corresponding ketone is obtained in a yield of about 90%.

Example 18 grs. of cyclohexanol (1 mole) are mixed with 69.5 grs. of calcium bromate solution and 8 grs. of hydrobromic acid solution and the mixture is kept for 3 hours at 35-40 C.

Cyclohexanone is thus obtained theoretical yield.

in a nearly Example 19 90 grs. (1 mole) oi'butylene glycol (1:3) are mixed with 46.3 grs..oi calcium bromate solution and 5 grs. of hydrobromic acid solution, the'mixture is kept at 35 to 40 C. for 6 hours and then heated to 50 C. for a few minutes. The oxidation has attacked to 80% the secondary hydroxyl group and only to 20% the primary hydroxyl group.

Erample 20 In order to show the promoting effect or copper (in the form of cupric ion) the following comparative experiments were made in which three batches. each containing 72 grs; of ethyl alcohol (96%) and 15 grs. oi hydrobromic acid solution, were oxidized with equivalent (as to the a. '70 grs. or calcium bromate solution. Residual bromate after:

Per cent -1 hour 40 2 hours 19 2 /2 hours b. 56 grs. of calcium bromate solution; plus 22.4 grs. of copper bromate solution (24%) (concentration of copper ion 0.1 gram atom per liter).

Residual bromate after:

Per cent 1 hour 27 2 hours 1.6 2 /2 hours Nil 0. 111 grs. of copper bromate solution (2MB) (concentration of copper ion about 0.44 gram atom per. liter) Residual bromate after 1 hour, nil.

The whole bromate and even 85% of the free bromine were consumed after 50 minutes.

Modifications of this invention which would occur to one skilled in the art are to be included in the scope of this invention as defined in the following claims,

We claim:

oxygen andwhich iscap'able, oi oxidizing bromide iontobromine in aqueous solution in the teme nereture range of about 3040," c.,-m the presence of free bromine in amolal concentration between about 0.01 and about 0.5. mole per gram atom of available oxygen in the oxidizing agent.

3; A process for the oxidation or a primary alkanol to a carboxylic acid which comprises contacting said alkanol inthe liquid phase at an elevated temperature with an inorganic oxidizing agent which contains an element selected from the group consisting of halogen and oxygen and which is capable oi. oxidizing bromide ion to bromine in aqueoussolution in the temperature range of about -80'C., in the presence of free bromine. in a concentration between about 0.01 and about 0.5 mol per gram atom of available oxygenin the oxidizingagen't;

4. A process according to claim 3 in which an excess of said alkanol is employed, and an ester isproduced. Y

5. A process for the. oxidation oi a secondary alkanolto a ketone whichcomprises contactin said alkanol in the liquid phase at an elevated temperature with an inorganic oxidizing agent which contains an. element selected from the 1. A process of non-disruptively oxidizing compounds selected from the class consisting of primary alkanols, secondary alkanols and alkanols, wherein the oxidation is performed in the liquid phase by the combined action of an amount of free bromine which is stolchiometrically small in proportion to the amount of the compound to be oxidized, and an amount stoichiometrically corresponding to the. desired amount of oxidation product, of an inorganic oxidizing agent which contains an element selected ture with an aqueoussolutionv of a solid inorganic oxidizing agent which contains an element .se-[ lected from the group consisting of halogen and in the oxidizing agent;

group consisting of halogen and: oxygen and which is capable ofoxidizing bromide ion to bromine in aqueous solution in the temperature range oi. about 30-80 0.. in the presence oi tree bromine in a molal concentration between about 0.01 and about 0.5 mol per gram atom availableoxygen 6. A process for the oxidation of an alkanol to an organic carboxylic acid, which comprises contacting said alkanol in the liquid phase 'at an elevated temperature with an inorganic oxidizing agent which contains an element selected from the group consisting oi halogen and oxygen and which is capable of oxidizing bromide ion to bromine in aqueous solution in the temperature range of 30-80 C., in the presence 01' free bromine in a molal concentration between about 0.01 and about 0.5 mol per mol of oxidizing agent.

7. A process according to claim 6 in which an alcohol is present in the reaction mixture and ane'steris produced.

8. A process according to claim 1, which is carried out in the presence of an oxidizing catalyst.

9. A process according to claim 2 in which the oxidizing agent contains both halogen and oxygen atoms.

10. A. process according to claim 2 in which the oxidizing agent is a bromate salt.

11. A process according to claim' .2 in which the oxidizing agent is an oxide of an amphoteric metal in a valence state of at least +4.

12. -A process according to claim 2 in which the oxidizing agent is manganese dioxide. v

13. A process according to claim 2 in which the oxidizing agentis chlorine.

14. A process according to claim 3 in which the alkanol is a polyhydric alkanol containing both a primary and a secondary hydroxyl group and the corresponding hydroxy ketone and keto acid areproduced.

15. -A process according to claim 2 in which the reaction mixture is maintained at its boilin point, and the reaction product is boiled off as formed. 4

a 16. A process for the oxidation of a Prim y alcohol-to an ester which comprises contacting an excessoi said alcohol inthe liquid phase at 75.

an elevatedtemperature with an aqueous solu- 'tion ,or a bromate salt. in the presence or free bromine in a concentration not greater than about 0.5 mole per gram atom 01 available oxygen in the oxidizing agent.

LADISLAUS GUZIILAUME FARKAS.

OZJASZ scHAcaTER.

REFERENCES CITED The following references are of .record in the flle of this patent:

UNITED STATES PATENTS OTHER REFERENCES Mare]: and Hahn, The Catalytic Oxidation 01 Organic Compounds in the Vapor Phase" (1932). pale 350. v

Certificate of Correction Patent No. 2,444,924. Jul 13, 1948,

LADISLAUS GUILLAUME FARKAS ET AL.

It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows: Column 9, line 55, claim 1, for the word alkanols-, third occurrence, read alkanals; line 71, claim 2,"for the syllable kanols" read Icanals; and that the saiil Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Ofiice.

Signed and 21st day of September, A, D. 1948.

moms F. MURPHY,

- Am'mmt Omnmim'oner of Patents. 

